msem-instigator

Haste
When Inciting Bard enters, other creatures you control get +1/+0 and gain haste until end of turn.

Equipped creature gets +3/+2 and must be blocked by a creature that doesn't share a color with it if able.
Equip {4}

Spells and abilities you control that target Inconspicuous Sheep cost {1} less.
As long as Inconspicuous Sheep is enchanted or equipped, they're a 3/3 legendary Sheep Rogue named Agent S.

As a permanent you control explores an Aura, you may put it onto the battlefield attached to Inconspicuous Stowaway.
As long as Inconspicuous Stowaway is enchanted or equipped, she's a legendary 2/3 Cat Rogue named Agent C and has double strike.

Create a tapped colorless Powercell artifact token with “{T}: Add {C}.” It doesn't untap during its controller's next untap step.

Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)
Whenever Indebted Burglar becomes blocked, defending player loses 1 life.

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
{1}: Target creature in Indomitable Anchorite's pack gains indestructible until end of turn. (Two or more creatures you control with equal power are in a pack.)

{T}: Add {C}.
{5}, {T}: Put a +1/+1 counter on target creature you control. Activate only as a sorcery.

Enchant creature
Enchanted creature gets +3/+2 and attacks each combat if able.

Creatures you control attacking causes their death knell to trigger.
Death knell — Indomitable Spirit gets +2/+2 and gains trample until end of turn. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

Target creature you control deals damage equal to its power to target creature you don't control.
Create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

{T}, Pay 1 life: Add {B} or {R}.
{2}, {T}, Sacrifice Industrial District and another permanent: Draw a card. Activate only during your turn.

Create three 1/1 red Human creature tokens with haste. Sacrifice those tokens at the beginning of the next end step.
Draw a card.

This spell can't be countered.
Inescapable Blaze deals 6 damage to any target.

Whenever Infernal Barrier is dealt damage, it deals 1 damage to each opponent.

Enchant creature
At the beginning of combat on your turn, create a token that's a copy of enchanted creature, except it has haste. Exile that token at the beginning of the next end step.

Infernal Flames deals 3 damage to target player or planeswalker.
Tether (Then if you cast this from your hand, you may exile it tethered to a creature you control. When it dies, you may cast this from exile without paying its mana cost.)

Enchant creature
Enchanted creature gets +3/+0 and has trample.
Madness {1}{R} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Whenever you cast an instant or sorcery spell, Infernal Immolator deals 2 damage to each opponent.

Enchant creature
Enchanted creature has “{R}, {T}: Create an X/1 red Elemental creature token with haste and trample, where X is this creature's power. Exile that token at the beginning of the next end step.”

Haste
When Inferno Forerunner enters, you may have target creature gain haste until end of turn.

Inferno Lash deals 2 damage to target creature or planeswalker. When it does, torment that permanent's controller. (They lose 3 life unless they discard a card or sacrifice a nonland permanent.)

Create two 1/1 green Insect creature tokens, then put a +1/+1 counter on target creature you control for each Insect you control.

Whenever a creature you control with power 4 or greater deals combat damage to a player, you may draw a card.